The investigator proposes to develop a lightweight, truly portable multi-channel electrophysiological system capable of doing full-scale routine clinical EEG and evoked potential procedures in a wide range of setting, including inpatient, outpatient, and environments where either battery power or complete electrical isolation is necessary. The system is to have 24 high-gain EEG channels, 4 intermediate-gain EOG or EMG channels, 4 single-ended instrument inputs, 2 GSR channels, 2 dedicated auditory brain stem response channels, 1 dedicated EKG channel, and 2 impedance pneumograph channels. The CPU is to be a notebook computer with a high resolution VGA screen, with 450 mega-bytes of data storage and an integrated high speed digital signal processor. The system is to provide user adjustable filtering, automatic impedance checking, and automatic amplifier calibration. It is expected to weigh less than 20 pounds with the approximate physical dimensions of an attach case and be capable of operating on battery power for 7 to 8 hours. A retail price of approximately $18,000.00 is projected.